Torque actuated reversible gear reduction assembly



March 22, 1966 p M, TQMARO, JR 3,241,385

TORQUE ACTUATED REVERSIBLE GEAR REDUCTION ASSEMBLY Filed June 22, 1962 5 Sheets-Sheet 1 I l l I 90 E S \.l m

INVENTOR. PATR/CK /l/l. TOM/QRO da BY @M ATTORNEYS March 22, 1966 P. M. ToMARo, JR

TORQUE ACTUATED REVERSIBLE GEAR REDUCTION ASSEMBLY Filed June 22, 1962 5 Sheets-Sheet 2 72M@ @f7/Z2 ATTORNEYS March 22, 1966 P, M TQMMQQl JR 3,241,385

TORQUE ACTUATED REVERSIBLE GEAR REDUCTION ASSEMBLY Filed June 22, 1962 5 SheBllS--SheMy 3 INVENTOR P4 TR/CA/ /l/l Tav/,4R0 J.

ATTORNEYS United States Patent O 3,241,385 TGRQUE ACTUATED REVERSIBLE GEAR REDUCTION ASSEMBLY Patrick M. Tomaro, Jr., Maplewood, NJ., assgnor, by

mesne assignments, to The Lionel Toy Corporation,

Wilmington, Del., a corporation of Delaware Filed June 22, 1962, Ser. No. 204,460 3 Claims. (Cl. 74--354) This invention relates to motor and gear train assemblies. More particularly, this invention relates to a miniaturized motor and speed reduction gear assembly having particular utility as a means for rotatably positioning the shaft of a potentiometer or the like.

There are numerous applications wherein it is desirable to position a rotatable shaft by remote control. For example, in stereophonic systems it is necessary to properly balance the two audio channels with respect to the listeners position to achieve a proper stereophonic effect. The controls for the system are generally located away from this position and it is diiiicult to adjust the system at one location so that the sound is properly balanced at another location. Thus, it is desirable to have a simple remote control system wherein the controls may be located at any point with respect to the speakers, so that a listener, regardless of his location, can readily adjust a potentiometer to balance the two channels.

The prior art has suggested a number of different methods for achieving this objective. For instance, one method employs a small, synchronous motor in combination with the potentiometer and a gear reduction assembly to reduce the angular Velocity of the rotor shaft to a level suitable for balancing the potentiometer. However, because of the huge inertia of the gear reduction system, which may reduce the speed by a factor of one hundred or more, in these systems it is practically impossible to manually a-djust the potentiometer, which for various reasons might be desirable.

Accordingly, it is an object of this invention to provide a simplified motor and gear train assembly for positioning a rotatable shaft while permitting manual adjustment thereof.

Another object is to provide a miniaturized gear train assembly for use with a reversible motor whereinthe outlet shaft is driven in accordance with the direction of the rotation of the motor.

Still another object is to provide a simplified gear train assembly wherein the output shaft is disconnected `from theA assembly when the input shaft is not rotated.

Yet another object is to provide a simplified means for remotely controlling a potentiometer or the like.

The objects of the invention are accomplished by coupling a reversible, synchronous motor and gear train assembly to the rotatable object to be positioned. The electrical controls for the motor are situated at the operators location so that he can determine the direction and extent of rotation. The gear train assembly includes a movable gear which, in response to energization of the motor, is adapted to mesh with one of two intermediate output gears depending upon the direction of rotation of the motor. The movable gear is springbiased to a center position where it meshes with neither intermediate gear when the motor is stationary. Both of the intermediate gears are coupled to an output shaft and each will cause the shaft to rotate in a different direction. When the motor is not operated and the movable gear is returned to its center position, the output shaft is effectively disconnected from the main body of the gear train assembly.

A more complete description of the manner in which the above objectives are accomplished will be given 3,241,385 Patented Mar. 22, 1966 with reference to the following specification and drawings wherein:

FIG. 1 represents a side view of the motor and gear train assembly in conjunction with a potentiometer;

FIG. 2 is a cross-sectional view of the apparatus of FIG. 1;

FIG. 3 is an exploded perspective View of the gear train assembly;

FIG. 4 is a top View of the gear train assembly;

FIG. 5 illustrates the bottom plate of the gear train assembly;

FIG. 6 is a view through the plane 6-6 of FIG. l;

FIG. 7 is a cross-sectional View through the plane 7-'7 of FIG. 2;

FIGS. 8, 9 and 10 are cross-sectional views through the plane 6-6 of FIG. 1 illustrating the operation of the movable gear;

FIG. 11 is an exploded View of the motor;

FIG. 11a illustrates the rotor structure of the motor;

FIG. 12 is a view through the plane 12-12 of FIG. 1;

FIG. 13 is a top view of one of the stator sections of the motor through the plane 13-13 of FIG. 2;

FIG. 14 is a bottom View of the other stator section of the motor;

FIG. 15 is a View along the line 15-15 of FIG. 2 showing the pole piece construction and rotor; and

FIG. 16 is a schematic showing of the electrical circuit, motor, gear train and potentiometer.

Referring now to FIGS. 1 and 2, the assembled unit is shown in combination with a potentiometer 24. The motor is indicated at 20 and includes an output gear 21 which is secured to the rotor. The motor is attached to a gear train assembly 22, which reduces the angular velocity of output gear 21 in order to adjust potentiometer 24. Gear assembly 22 includes an output shaft 26 which is adapted to rotate the movable contact of the potentiometer, and, in addition, the potentiometer may be controlled manually in a conventional manner by means of a shaft 28.

The operation and construction of motor 2t) will be described in greater detail below. For purposes of explanation, it is suicient to note at this point that the motor may be a reversible, synchronous motor. Depending upon the manner in which the coils of the motor are energized, the rotor, and thus the output gear 2l, will rotate in a clockwise or counterclockwise direction. If the invention is to be used, for example, to adjust the balance of a stereophonic system, potentiometer 24 will be the balancing means and will be located in the preamplifier. The shaft 28 will extend from the preamplifier casing where it may be manually rotated to balance the system. The motor 20 and gear train assembly 22 will extend into the interior of the casing. The leads controlling the motor may be connected to a small exterior unit including switch means for reversing the direction of rotation of the motor. The listener may then cause the movable contact of the potentiometer to rotate in either direction until the system is properly balance. At that point, the coils of the motor are de-energized which, in accordance with the invention, automatically disengages the output shaft 26 of the potentiometer 24 from the gear train assembly 22, permitting manual adjustment of shaft 28. If the output shaft 26 were not disconnected from lthe gear assembly 22, it would be extremely ditlicult to manually adjust the potentiometer because of the inertia` of the gear reduction necessary to reduce the relatively high speed of output gear 21 to the angular velocity necessary for adjustment purposes.

The operation of the gear train assembly will be described in detail with additional reference to FIGS. 3-7. FIG. 3 is an exploded view of the gear train assembly. FIGS. 4 and 5 are top and bottom views of the assembly,

respectively, while FIGS. 6 and 7 are views through the planes 6-6 and 7 7, respectively, of FIGS. 1 and 2. As shown most clearly in FIGS. l-3, the output gear 21, attached to the rotor of the motor 20, extends into the gear train assembly 22. The assembly is supported by means of a top plate 30, a middle plate 31 and a bottom plate 32. The plates are fixed and held together by horizontal supporting posts 33, 34 and 35, spaced about the periphery of the assembly. Upper screws 36 (FIG. 4) and lower screws 37 extend into the posts to secure the assembly together. Middle plate 31 may be secured by means of small cut-out portions which are received in suitable grooves of the supporting posts.

The output gear 21 extends through the top plate 3@ and into engagement with a pair of offset coaxial gears 38 and 39. Gear 21 engages the larger diameter gear 38 which along with gear 39 is secured to a pin 40 journaled in top plate and middle plate 31. Gear 39 engages a large diameter gear 41 which is coaxial with a smaller gear 42. Gears 41 and 42 are secured to a pin 43 which is rotatably supported in a stationary post 44 extending from the center of middle plate 31 toward the inner plate 30. p

In accordance with the invention, a pair of movable coaxial gears 45 and 4,6 are secured to a pin 47 which is journaled in a pivotable yoke 4.8.. Yoke 48 is mounted between inner plate 39 and middle plate 31 by means of a post 50 which is pivotally supported in these two plates at a point toward the periphery of the gear train assembly between 'supporting posts 33 and 35. Yoke 48 includes an aperture 51 which straddles the stationary post 44 on which the pair of central coaxial gears 41 and 42 are supported. As illustrated, yoke 48 is secured to post 50 at a slight distance above the upper surface of middle plate 31V. gears 45land 46, a small downwardly extending post 52 extends into an opening 49 (FIG. 7) provided in plate 31. A V-shapedspring 53 is situated between the middle plate 31 and yoke 48 with its apex passing around the outside of post 52 and the extremities of its arms braced againstrsupporting posts 33 and 35, as shown in FIGS. 3 and 7. If desired, the spring may be wound around post 52 or any other spring configuration may be employed within the spirit of the invention,

Spring 53 is adjusted to position yoke 48 so that gear 46 is centered between and out of engagement with two pairs of intermediate coaxial output gears 54, 55 and 53, 59, respectively. Gears 54 and 55 are secured to a pin 56, and gears 58 and 59 are secured to a pin 60. Middle plate 31 has a pair of integrally formed L-shaped arms 62 and 64 extending downwardly towards outer plate 32 as shown in FIGS. 1 and 2. Pin 56 is journaled in arm 62 and middle plate 31, and pin 60 is journaled in arm 64 and plate 31 to permit rotation of whichever intermediate gear is engaged by the movable gear 46, as will be described below. The small diameter gears 55 and 59 of the intermediate coaxial gears are in permanent engagement with an output gear 74 secured to output shaft 26, and since each intermediate pair of gears is caused to rotate in a different direction, the direction of rotation of shaft 26 is determined by which pair of gears is engaged by movable gear 46.

The movement of gear 46 into engagement with one of the pairs of intermediate coaxial gears is enabled by means of a clutch pinion 66 which is best illustrated in FIG. 2. Pinion 66 engages the large diameter movable gear 45. The pinion may be made of a non-metallic material and includes a hollow cylindrical base portion 67 extending toward middle plate 31. The clutch pinion 66 is rotatably supported in plates 31 and 30 by means of a downwardly extending pin 68 and an upwardly cxtending pin 7@ concentric with base portion 67.

A clutch pinion spring 71, surrounding post 69, is tensioned between top plate 30 and a clutch pinion washer 72 (FIG. 6) which rests above pinion 66 and helps maintain the pinion in engagement with gear 45. Thus, al-

Mounted on yoke 4S beneath coaxial 4 though the clutch pinion 66'- is capable of rotation, ther force of spring 71 causes friction between middle plate,- 31 and the bottom of the cylindrical base 67 which tends; to inhibit the rotation of pinion 66.

The operation of the gear train' assembly will now be,A described in greater detail with specific reference to FIG.- URES 8, 9 and 10, which are cross-sectional views through.l the plane 6-6` of FIG. 1. These figures illustrate the manner in which the rotation of the yoke enables gear 46 to drive one of the two intermediate coaxial gears. It will be recalled that under normal conditions, the; movable gear 46 is biased by spring 53 to a position between intermediate gears 54 and 5S where it is in engagement with neither gear. Under these conditions, the output gear 74, and thus the potentiometer 24, is effectively disconnected from the gear train assembly. Depending upon the direction of rotation of the output gear 21 of motor 29, it is necessary to engage one of the two pairs of intermediate coaxial gears. Thus, assume gear 21 is rotating in a clockwise direction. Coaxial gears 36 and 39 which are connected therewith, rotate in a counterclockwise direction, while coaxial gears 41 and 42 which are in engagement with gear 39 rotate in a clockwise direction. Movable gears 45 and 46 which are in engagement with gear 42 also rotate in a counterclockwise direction. Since intermediate gears 54 and 58 are in engagement with none of the abovementioned gears, neither gear immediately responds to the rotation of the output gear 21. However, since clutch pinion 66 is friction `biased against middle plate 31 by the action of spring 71, the pinion tends to resist rotation causing the entire movable gear 45 to tend to move in a counterclockwise direction around the friction pinion 66. Gear 47 and gear 46 are mounted on a yoke 48 which is capable of a pivotable movement about pivot post 50, and therefore coaxial gears 45 and 46 move to the position shown in FIG. 9 where the small diameter gear 46 engages the large diameter gear 54. Since gear 46 is secured to gear 4S, which in turn engages small central gear 42, intermediate gear 54 will rotate in a clockwise direction causing gear 55, which meshes with output gear 74, to rotate output shaft 26 in a counterclockwise direction at a greatly reduced speed. The movement of the yoke is limited by engagement of gear 46 with intermediate gear 54, and when the frictional `forces between the clutch pinion 66 and the middle plate 31 are overcome, the pinion will be forced to rotate also. As the yoke 48 pivots from its center position illustrated in FIG. 8, it acts against the biasing force of spring 53, so that even when gear 46 engages intermediate gear 54 it is being urged to its center position.

When the movable contact of potentiometer 24 has Ibeen rotated to a desired position, the operator may throw a switch to halt operation of the motor. As soon as gear 21 stops rotating, the force that is holding gear 46 in engagement with intermediate gear 54 is removed, and the centering spring 53 returns the yoke 43 to its initial position indicated in FIG. 8. During the return movement, pinion 66 remains fixed, and movable gears 46 and 45 drive the front end of the gear train and motor in reverse as yoke 4S pivots `back to its neutral position under the influence of spring 53. As above-discussed, at this point the movable gear 46 is centered between the two pairs of intermediate `coaxial gears effectively disconnecting the output shaft 26 from the main body of the gear train assembly. In this state, it is relatively easy to `manually adjust the potentiometer by means of shaft 28, since it is only necessary to push `against the intermediate output gears which are in engagement with output gear 74.

If the operator thereafter causes the motor to rotate in the reverse direction so that gear 21 is turning in a counterclockwise direction, the action is similar to that described above. In this case, however, as shown in.

FIG. l0, the movable gears `45 and 46 rotate with yoke 48 in a counterclockwise direction about pivot post 50, causing gear 46 to move into engagement with intermediate output gear 58. When the energization is removed from the coils of the motor and gear 21 stops rotating, centering spring 53 returns the yoke to its center position illustrated in FIG. 8, disengaging gear 46 from either intermediate output gear 58 or 54.

Potentiometer 24 includes terminals 76, 77, 78 and 79 suported on an insulation board 80 in a conventional manner as illustrated in FIG. 7. The potentiometer is mounted on the inner surface of bottom plate 32 and includes a threaded sleeve 86 which extends through plate 32 and is secured thereto by means of an inner nut 82, an external Washer 83, and an external nut 84. A C- clip 88 retains the shaft 28 in its proper position within sleeve 86.

Motor is a synchronous motor of the hysteresis type. Such motors are economical to manufacture, so that despite their relatively low efficiency they are particularly suitable for the present purposes in view of the light load which must be driven. Because of improved techniques, these motors have found increasing favor wherein a small synchronous motor must be used to drive relatively light loads, such as a clock, potentiometer or the like.

Although a specific embodiment of the invention has been disclosed, many modifications thereof will 'be obvious to one skilled in the art, and the invention should not be limited except as defined in the following claims.

I claim:

1. A gear reduction assembly for coupling the driving shaft of a reversible motor to a single output shaft whereby said output shaft may be driven lby said motor, said assembly comprising an input gear operatively coupled to the drive shaft and rotatable in response to the rotation of said driving shaft, an output gear coupled to said output shaft, a pair of intermediate gears in en- `gagement with said output gear and means for decoupling said driving and output shafts at times when said motor is not running whereby to facilitate manual control of said output shaft at such times, said means comprising a pair of coaxial movable gears having different diameters, a subframe for mounting said coaxial gears, said frame being pivotably mounted on an axis remote from the axis -of the input gear for providing transverse movement thereof, the first of said coaxial movable gears being in engagement with said input gear whereby said coaxial movable gears can traverse a portion of the circumference of said input gear, a pinion supported within said assembly and frictionally biased against rotation, said pinion being coupled to the rst of said coaxial movable gears to permit said coaxial movable gears to traverse said input gear responsive to the rotation -of said driving shaft whereby the second of said coaxial movable gears is moved into engagement with one of said intermediate gears depending upon the direction in which said driving shaft is rotating, and spring means biased by the movement of said coaxial movable gears for moving said second coaxial gear out of engagement rotatable in response to the rotation of said driving shaft,`

an output gear coupled to said output shaft, a pair of intermediate gears in engagement with said output gear, and means for decoupling said driving and output shafts at times when said motor is not running whereby to facilitate manual contr-ol of said output shaft at such times, said means comprising a pair of coaxial movable gears having different diameters, a subframe for mounting said coaxial gears, said frame being pivotably mounted on an axis remote from the axis of the input gear Ifor providing transverse movement thereof, the first of said coaxial movable gears being in engagement with said -input gear whereby said coaxial movable gears can traverse a portion of the circumference of said input gear, a pinion supported within said assembly and frictionally biased against rotation, said pinion being coupled to the first of said coaxial movable gears to thereby permit said coaxial movable gears to traverse said input gear responsive to the rotation of said driving shaft whereby the other of said coaxial movable gears is moved into engagement with one of said intermediate gears depending upon the direction in which said driving shaft is rotating, and spring means biased by the movement of said coaxial movable gears for moving said other coaxial gear out of engagement with either of said intermediate gears when said motor is not running.

3. A gear reduction assembly according to claim 1 wherein said intermediate gears each comprises a pair of coaxial gears, one of said intermediate coaxial gears being in engagement with said output gear and the other of said intermediate coaxial gears being adapted to engage said other movable coaxial gear.

References Cited bythe Examiner UNITED STATES PATENTS 1,380,874 6/1921 Valent 74-354 1,841,950 1/1932 Hinman 74-405 X 2,046,412 7/ 1936 Reynolds 74-354 2,094,669 10/1937 Pratt 74-353 X 2,506,562 5/1950 Wait 74--812 X 2,587,038 2/1952 Goodell 74-354 X 2,828,648 4/1958 Hazard 74--354 X 2,896,873 7/1959 Mageoch 74--354 X 2,972,900 2/ 1961 Bailey et al. 74-354 2,978,923 4/ 1961 Carlson 74--354 X 3,028,767 4/ 1962 Moore 74-354 X 3,040,599 6/ 1962 Carlson 74--354 X 3,168,840 2/ 1965 Williams 74-354 X FOREIGN PATENTS 789,165 1/ 1958 Great Britain.

DON A. WAITE, Primary Examiner.

BROUGHTON G. DURHAM, Examiner. 

1. A GEAR REDUCTION ASSEMBLY FOR COUPLING THE DRIVING SHAFT OF A REVERSIBLE MOTOR TO A SINGLE OUTPUT SHAFT WHEREBY SAID OUTPUT SHAFT MAY BE DRIVEN BY SAID MOTOR, SAID ASSEMBLY COMPRISING AN INPUT GEAR OPERATIVELY COUPLED TO THE DRIVE SHAFT AND ROTATABLE IN RESPONSE TO THE ROTATION OF SAID DRIVING SHAFT, AN OUTPUT GEAR COUPLED TO SAID OUTPUT SHAFT, A PAIR OF INTERMEDIATE GEARS IN ENGAGEMENT WITH SAID OUTPUT GEAR AND MEANS FOR DECOUPLING SAID DRIVING AND OUTPUT SHAFTS AT TIMES WHEN SAID MOTOR IS NOT RUNNING WHEREBY TO FACILITATE MANUAL CONTROL OF SAID OUTPUT SHAFT AT SUCH TIMES, SAID MEANS COMPRISING A PAIR OF COAXIAL MOVABLE GEARS HAVING DIFFERENT DIAMETERS, A SUBFRAME FOR MOUNTING SAID COAXIAL GEARS, SAID FRAME BEING PIVOTABLY MOUNTED ON AN AXIS REMOTE FROM THE AXIS OF THE INPUT GEAR FOR PROVIDING TRANSVERSE MOVEMENT THEREOF, THE FIRST OF SAID COAXIAL MOVABLE GEARS BEING IN ENGAGEMENT WITH SAID INPUT GEAR WHEREBY SAID COAXIAL MOVABLE GEARS CAN TRANSVERSE A PORTION OF THE CIRCUMFERENCE OF SAID INPUT GEAR, A PINION SUPPORTED WITHIN SAID ASSEMBLY AND FRICTIONALLY BIASED AGAINST ROTATION, SAID PINION BEING COUPLED TO THE FIRST OF SAID COAXIAL MOVABLE GEARS TO PERMIT SAID COAXIAL MOVABLE GEARS TO TRAVERSE SAID INPUT GEAR RESPONSIVE TO THE ROTATION OF SAID DRIVING SHAFT WHEREBY THE SECOND OF SID COAXIAL MOVABLE GEARS IS MOVED INTO ENGAGEMENT WITH ONE OF SAID INTERMEDIATE, GEARS DEPENDING UPON THE DIRECTION IN WHICH SAID DRIVING SHAFT IS ROTATING, AND SPRING MEANS BIASED BY THE MOVEMENT OF SAID COAXIAL MOVABLE GEARS FOR MOVING SAID SECOND COAXIAL GEAR OUT OF ENGAGEMENT WITH EITHER OF SAID INTERMEDIATE GEARS WHEN SAID MOTOR IS NOT RUNNING. 